Equipped with one MH60 Romeo helicopter and a mission bay for an unmanned system

Accommodates 180 crew

The build is due to begin in 2020, with 1,500 jobs to be created in South Australia, and an additional 2,500 jobs elsewhere around the country.

But the Australian Manufacturing Workers Union (AMWU) said it feared there could still be a gap in work, between the end of the Air Warfare Destroyer project and the beginning of the Future Frigates project.

"The Offshore Patrol Vessel commences cutting of steel in the later part of this year, but that project will only facilitate 300 to 400 jobs," AMWU assistant secretary Glenn Thompson said.

"There's approximately 900 to 950 [people] working on the Air Warfare Destroyer as we speak, so we want to ensure we maintain that skill base.

"It's great that we've got the announcement — now we're calling on the Government to ensure the contract with BAE ensures any surplus workers are transitioned to this project.

"Minister Pyne and the Government need to give those 500 workers and their families some certainty in relation to their future."

Liberal party filling Labor's 'valley of death': PM

During his announcement on Friday, Prime Minister Malcolm Turnbull said the Federal Government had been forced to catch up and fill the jobs "valley of death" left by the former Labor government.

"The ebb and flow of jobs, that is [absolutely the consequence] of a shocking abdication of the Labor Party … they failed to do their duty as the government of Australia to build the ships our navy needs," he said.